Thanks Jason,

I thought I put that one on top because I have experienced it more than once (loose canopy), and what a difference it made! Also what Russell Honea writes applies in most cases, I insulated my plane with a small plastic-like material called "Crepla" found in most hobbyshops and do-it-yourself type of stores, very light, comes in different thickness (1 to 5mm, maybe more) and glues to most materials with a small drop of CA. Carb filters are a good way, even better it is to look for carb air *behind* the firewall (inside the fuselage) using for instance a pre-bent fiberglass tube as air intake. (candles are btw a very good way for doing your own).
A good 4 blade prop, efficiently swung, generates less noise than a 2 blade prop, not balanced. Other sources that come to my mind: spinner caps, belly pans, canopies, servo hatches, bowden-tubes, tank and fuel line inside the fuse, antenna... In other words, pretty much anything!

As for "cheating" with the measurement, I'm sure Tuomas acts in good spirit but I can assure you that with very modest time and money investment (while building, a couple of hours and maybe 30 Euros) you can have full power AND stay safely below 90 dBA even in wind. My plane does 89 dBA (specs above), my former plane did 88 (Supertigre 2300, Greve pipe, 15x11 4-blade, averything softmounted on rubber blocs, pipe 'floating' inside fiberglass tube and suspended with fuel line).

We had to do it because otherwise we wouldn't be able to fly at all (remember, Switzerland...), but I couldn't personally think doing it in any other way: silent and clean - i like it! Necessity for us, but also a pleasure to fly - guaranteed!

Regards,
-Fabrizio